A protective film (removable pressure-sensitive adhesive sheet) has been attached to an automotive body/part in order to prevent damage during transportation or storage. Particularly in automobile parts A resin automotive bumper on which a paint is applied has been increasingly used instead of a metal bumper in order to reduce the weight of automobiles.
Since a paint coat formed on a resin bumper cannot be cured at a high temperature, the paint coat may be incompletely cured. When a paint coat-protecting removable pressure-sensitive adhesive sheet is attached to such a paint coat (incompletely-cured film), swelling (i.e., a phenomenon in which a change in shape of the pressure-sensitive adhesive sheet such as a small wrinkle, protrusion, or the like formed when attaching the removable pressure-sensitive adhesive sheet is transferred to the paint coat so that the paint coat is deformed), whitening (i.e., a phenomenon in which the composition of the paint coat becomes non-uniform due to the compatibility with the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, so that the paint coat is whitened after the pressure-sensitive adhesive sheet has been removed), adhesive transfer (i.e., a phenomenon in which part of the pressure-sensitive adhesive layer is transferred to the paint coat when removing the pressure-sensitive adhesive sheet), or the like may occur.
Pressure-sensitive adhesive sheets disclosed in Patent Documents 1 to 4 have been known as the paint coat-protecting removable pressure-sensitive adhesive sheet. However, the removable pressure-sensitive adhesive sheets disclosed in Patent Documents 1 to 4 cannot sufficiently protect an incompletely-cured film.
Patent Document 5 discloses an aqueous emulsion-type pressure-sensitive adhesive that contains a copolymer obtained by emulsion polymerization of a monomer composition that contains ethylene, an aliphatic vinyl carboxylate having 8 to 15 carbon atoms, and an alkyl (meth)acrylate in a specific ratio.
However, Patent Document 5 is silent about a removable pressure-sensitive adhesive sheet that is attached to an incompletely-cured film (paint coat).